This invention relates to an electrical connector for use in electric or electronic appliances such as servers, super computers and the like, and more particularly to an improved electrical connector capable of minimizing crosstalk when being connected to cables.
In recent years, with the miniaturization of electric or electronic appliances, the requirement of miniaturization for electrical connector has put more severe pressure on manufacturers of connectors. In many cases, generally, an electrical connector comprises insulators formed of electrically insulating materials and electric contacts formed of a conductive material. The electric contacts each comprise a contact portion to contact a mating object, a fixed portion to be fixed to the insulator and a connection portion to be connected to a substrate or a cable. The electric contacts are fixed to the insulator by press-fitting, hooking (lancing) or the like.
As pitches of electric contacts have become progressively narrower, flexible printed boards or patterns on substrates have been used as contact portions or connection portions instead of pluralities of electric contacts as disclosed in the following Patent Literature 1. Moreover, there has been proposed to connect a rigid printed board and a flexible printed board directly to each other as disclosed in the following Patent Literature 2.
Japanese Patent Application Opened No. H10-32,062 (1998) (Patent Literature 1) discloses a substrate and the like used as contact portions or connection portions instead of electric contacts. This opened application has an object to provide an electrical connector whose connectors provided on each of substrates can be fitted with each other regardless of positional shifting (of the order of 0.5 mm) between the substrates. For this purpose, an insulator is provided with means for holding and fixing electric contacts which are flexible. Disclosed are electric contacts constructed by attaching two contact members to each other, the contact members each having conductors interposed between an insulating layer A and an insulating layer B. In other words, flexible printed circuit boards are used as the contact members to increase floating when connectors are being fitted with each other.
The invention disclosed in Japanese Patent Application Opened No. H7-15,106 (1995) (Patent Literature 2) has an object to prevent degrading of electric characteristics such as deterioration in signal when rigid and flexible boards are directly connected. For this purpose, in contact patterns consisting of narrow patterns in the case that the rigid and flexible boards are directly connected, ground patterns are arranged at a rate of one ground pattern per n signal patterns. With such arrangement, impedance of the ground patterns is stabilized to minimize the influence of noise and static electricity, and to reduce deterioration in signals due to crosstalk noise between signal patterns, thereby preventing the deterioration of electric characteristics. In other words, the n signal patterns and the ground patterns are arranged in a manner that n signal patterns are interposed between the ground patterns, thereby stabilizing the impedance.
In recent years, with the miniaturization of electric and electronic appliances, the requirement for miniaturization of electrical connectors has put more severe pressure on manufacturers of connectors, resulting in the rapid promotion of small and light type connectors. With high speed transmission (speeding up of signal speeds), reduction in crosstalk has become absolutely necessary.
The invention disclosed in the Patent Literature 1 intends to increase the floating when the connectors are fitted, by using the flexible printed boards. In this invention, however, the connection portions are of the surface mounting type (SMT) and not to be connected to cables, and there is no distinction between the signal and ground lines. Moreover, the invention in the Patent Literature 1 does not intend to stabilize the impedance and reduce the crosstalk either.
The invention disclosed in the Patent Literature 2 intends to stabilize the impedance of contact patterns by arranging the ground patterns at a rate of one ground pattern per n signal patterns. Such a feature does not reduce the crosstalk.